Manual Device for Dispensing a Pasty Filler

ABSTRACT

A manual device, in particular for dental use, for dispensing a pasty filler, the viscosity of which may be reduced by the introduction of vibrational energy, comprises a device housing, a detachable container for the pasty filler that comprises an outlet nozzle at a front end thereof, vibration generation means with an oscillating body, and pressure generating means for exerting pressure on the pasty filler, wherein the vibration body is detachably connected to the container in a middle region thereof.

The present invention relates to a handheld tool according to thepreamble of claim 1, which is provided in particular for dental purposesand is designed to dispense a pasty filling material, the viscosity ofwhich can be reduced by supplying oscillation energy. Furthermore, thepresent invention relates to a container for accommodating a pastyfilling material, which can be used in such a handheld tool.

In medical technology, it is known to fill, and thus to repair, cavitiesin an animal or human body part or in a prosthesis with a fillingmaterial, for example after a defect has been eliminated by removal ofmaterial. For this purpose, use is made of curable filling materials,which are introduced into the cavity in a pasty or liquid state and thencure. In this case, a distinction should be made between a directfilling and an indirect filling. In a direct filling, only the fillingmaterial is introduced into the cavity so that it fills the cavity. Inan indirect filling, a preferably matching inlay insert containing thefilling material is inserted into the cavity so that the inlay insertconnects the insert to the wall of the cavity. In this case, not onlymechanical anchoring of the filling material in the cavity is important,but also sealed accommodation of the filling material in the cavity, inorder to avoid gaps which can be passed through by contamination andgerms, which can lead to inflammation in a body tissue and can destroythe preparation.

A typical application of an above-described preparation, in which thereare particular requirements with regard to the handheld tool and thehandling thereof, is tooth preparation in the oral cavity of a patientor in a practice head for learning purposes. In such a dental treatmentcase, there are particular requirements with regard to the structuralsize of the handpiece, since the oral cavity of a patient iscomparatively small and therefore, with necessary visibility being takeninto account, a structural size which is as small as possible should besought.

DE 100 01 513 A1 describes a method for filling a synthetic resin-basedtooth filling material into a cavity of a tooth and a handheld tool forcarrying out such a method, wherein, during filling, the fillingmaterial and a nozzle of the handheld tool are acted on with sound, inparticular with ultrasound, and the handheld tool has means which conveythe filling material out of a storage container in the nozzle. Thisknown method and handheld tool make it possible to use filling materialshaving a comparatively high content of fillers, which increase theviscosity of the filling material and thus reduce shrinkage and the riskof gaps forming during curing. In this previously known handheld tool,there is provided a lever device for conveying the filling material, andwhen this lever device is manually actuated an ultrasound source, inparticular a piezoelectric oscillator, is switched on at the same time,this ultrasound source or piezoelectric oscillator being arranged in therear region of the body of the handheld tool. The filling material isarranged in a cartridge, which can be inserted into a cutout arranged inthe front end region of the body of the handheld tool and fixed therein.When the lever device is manually actuated, the filling material isconveyed out by a feed ram which is connected to the lever device andacts on the rear end of the cartridge.

A comparable tool is also known from WO 2006/13639 A2 of the applicant.In this case, particular modifications to the handheld tool areproposed, which help to improve both the dispensing of the compositematerial and also the handling of the tool.

For reasons of hygiene, it would be advantageous to configure thestorage container for the composite material with the outlet nozzle inthe form of a cartridge, as a disposable or single-use article. For eachtreatment, a new cartridge could then be used, so that cleaning anddisinfection, which would otherwise be essential, can be avoided. On theother hand, the result of this solution is that a detachable connectionis necessary between the storage container and the handheld tool, andthis can lead to problems with regard to the effectiveness ofoscillation transmission and with the dispensing of the fillingmaterial.

It is therefore the object of the present invention to optimize theconcepts, known from the prior art, for dispensing a filling material,in order ultimately to open up the possibility of designing the storagecontainer for the pasty filling material in a detachable or exchangeablemanner, wherein nevertheless effective oscillation transmission anddispensing of the material should be ensured.

The object is achieved by a handheld tool which has the features of theindependent claims. Advantageous developments of the invention are thesubject-matter of the dependent claims.

In this case, according to a first aspect of the present invention, itis first of all provided that the container for the pasty fillingmaterial is configured so that it is detachably connected in a centralregion to an oscillating body of the handheld tool.

According to this first aspect, there is accordingly proposed a handheldtool, in particular for dental purposes, for dispensing a pasty fillingmaterial, the viscosity of which can be reduced by supplying oscillationenergy, having a tool housing, a detachable container for the pastyfilling material, the container having an outlet nozzle at its frontend, an oscillation generator having an oscillating body, andpressure-generating means for exerting pressure on the pasty fillingmaterial, wherein, according to the invention, the oscillating body isdetachably connected to the container in a central region of the latter.

Furthermore, according to this first aspect of the present invention,there is also proposed a container for use with a handheld tool asdescribed above, wherein the container is designed to accommodate apasty filling material and has at its front end an outlet nozzle.According to the invention, it is provided that the container has in itscentral region means for detachably connecting it to the handheld tool.

As is described in more detail in the following text, the configurationaccording to the invention of the container for the filling materialensures that the oscillations of the oscillating body are transmittedmore effectively to the container and accordingly the viscosity can bereduced more effectively when the filling material is dispensed.

In this case, according to an advantageous development of the invention,it is provided that the oscillating body is connected to the containervia a quick-action connection, in particular via a screw connection or abayonet connection. This enables easy fastening and detachment of thecontainer to and from the hand-held tool.

In this case, the container may have in its front region a cannula whichforms the outlet nozzle, wherein in this case the means for connectingthe container to the oscillating body are formed in particular at theend of the cannula. This ensures that the oscillations are transmittedeffectively to the filling material up to the time at which the pastyfilling material leaves the cannula. Preferably, the cannula in thiscase forms a separate component which is joined together to form thecontainer with a further component that forms an accommodating chamberfor the filling material. This further component that forms theaccommodating chamber for the filling material can then be arranged, inparticular in a state arranged on the handheld tool, with a perfect fitsubstantially within an accommodating opening in the oscillating body.The further component thus serves for guidance and for improvedintroduction of the optionally used thread for detachably fastening thecontainer to the handheld tool. Furthermore, the wall of the containerno longer has to be formed to be stable under pressure, since it can nowbe supported directly on the oscillating body and thus absorbs all theforces.

The two-part form of the container is furthermore advantageous since itmakes it possible to form the cannula in an effective and thuscost-effective manner. The cannula is in this case formed in particularin such a way that it has a conical clearance which is directed towardsthe front end. The effect of this clearance is that, during dispensing,the filling material is continuously subjected to shear stress, and theresult of this is that it is heated through more effectively and thusbecomes more fluid. This contributes to even further improved dispensingof the material.

Furthermore, the container may have in its rear region a pressurepiston, on which pressure-generating means of the handheld tool act todispense the filling material. The pressure-generating means may in thiscase have a piston rod which acts on the pressure piston.

In this case, according to a second aspect of the present invention itis furthermore possible for provision to be made of restoring means, inparticular one or more spring elements, with the aid of which the pistonrod is prestressed into a starting position. Following a change of thecontainer holding the filling material, the tool is thus immediatelyready for use again. The oscillation generator is preferably apneumatically drivable oscillation generator, wherein in this case acommon pressure supply for the oscillation generator and thepressure-generating means is then provided.

According to the second aspect of the present invention, there isaccordingly proposed a handheld tool, in particular for dental purposes,for dispensing a pasty filling material, the viscosity of which can bereduced by supplying oscillation energy, having a tool housing, adetachable container for the pasty filling material, said containerhaving an outlet nozzle at its front end, an oscillation generatorhaving an oscillating body, and pressure-generating means for exertingpressure on the pasty filling material, wherein, according to theinvention, the container has in its rear region a pressure piston andthe pressure-generating means have a piston rod which acts on thepressure piston in the container, and wherein furthermore restoringmeans, in particular one or more spring elements, for prestressing thepiston rod into a starting position are provided.

As already explained above, the automatic restoring of the piston rodleads to improved handling of the tool, since when the storage containeris changed no further activities are required in order to put thehandheld tool into the operating state. This, too, leads to it beingpossible for the storage container to be used in an easier and moreeffective manner as a single-use article.

Viewed overall, the present invention accordingly specifies an improvedconcept for dispensing filling material in order to produce toothfillings, wherein in particular the possibility of configuring thestorage container for the filling material having the outlet nozzle as asingle-use or disposable article is opened up.

The invention will be explained in more detail in the following text onthe basis of the accompanying drawing, in which:

FIG. 1 shows the overall view of a handheld tool according to theinvention in a lateral sectional illustration;

FIG. 2 shows an enlarged view of the front end region of the handheldtool with the container for the composite material fastened thereto; and

FIG. 3 shows the container for the composite material in a sectionalillustration.

The handheld tool according to the invention, which is designatedoverall by the reference number 1 in the Figures, has an elongate, inparticular rod-shaped, tool shaft 2, which is configured in a tube-likemanner to accommodate the various components of the tool 1. In thiscase, an oscillation generator 5 is arranged in particular in the frontregion of the tool shaft 2 and is coupled via oscillation transmissionmeans to a cartridge 30, which will be described in more detailhereinbelow. The cartridge 30 serves to accommodate and dispense afilling material 50, which can be liquefied by being subjected tooscillations in the audible sound or ultrasound range.

The handheld tool 1 furthermore supports the dispensing of the fillingmaterial 50 located in the cartridge 30, for which purposepressure-generating means 15 are formed in the central region of thetool shaft 2. These pressure-generating means 15, which will bedescribed in more detail hereinbelow, have in particular a piston rod 16which, during operation of the handheld tool 1, exerts pressure on apiston 40 located in the rear region of the cartridge 30, as a result ofwhich the material 50 located in the cartridge 30 is conveyed to thefront outlet opening 36 in an outlet nozzle 35.

A common pressure supply is provided for the oscillation generator 5 andfor the pressure-generating means 15. The handheld tool 1 is for thispurpose first of all equipped in its rear end region with a couplingpart 25, which allows the connection of the tool 1 to a hose which isknown per se and leads to a supply unit (not illustrated). The couplingpiece 25 can in this case be configured in such a way that the handheldtool 1 is allowed to rotate freely with respect to the supply hose.

The pressure of the compressed air made available by the supply hose isin this case first of all regulated via a pressure limiter 26 arrangedin the rear region of the shaft 2. This pressure limiter 26 is set viaan operating element 27, for example a setting ring, which is formed onthe outer circumference of the handheld tool 1. By rotating this settingring 27, the pressure can be increased or reduced as desired, and thusthe performance of the oscillation generator 5 and of thepressure-generating means 15 can be set. The pressure limiter 26furthermore ensures that pressure fluctuations that arise in the airsupply are equalized, so that a uniform working pressure is permanentlyprovided.

The compressed air, which is set by the pressure limiter 26 to a desiredpressure, is then first of all directed via a piston chamber 17 of thepressure-generating means 15 into the front region of the handheld tool1. Within this piston chamber 17 there is arranged a piston 18, which isconnected to the piston rod 16 and is formed in particular as a doublepiston. The use of a double piston increases the pressure force onaccount of the application area for the compressed air, increasedhereby, so that ultimately the piston rod 16 is pushed forward withsufficient force. Furthermore, a spring 19 is arranged in the frontregion of the piston chamber 17, this spring 19 being supported both onthe front end wall of the piston chamber 17 and on the piston 18. Thisspiral spring 19 serves as a restoring aid and ensures that after thehandheld tool 1 has been switched off, and thus the compressed air hasbeen interrupted, the piston 18 and the piston rod 16 connected to thepiston 18 are moved automatically into a starting position. Manualrestoring of the piston rod 16 is accordingly not necessary, and so oncea new cartridge 30 has been installed on the tool 1, the latter isautomatically ready for use.

The compressed air is furthermore also supplied to the oscillationgenerator 5, which is a pneumatic oscillation exciter, configured in aknown manner, for generating oscillations in the audible sound orultrasound range. The oscillation exciter has a resonant body 6, whichis mounted in an elastic manner and supported at its front and rearends. Furthermore, the resonant body is mounted via appropriate means 7in the shaft of the tool 1 so that it cannot rotate and is configured insuch a way that it is made to oscillate when compressed air is supplied.The oscillation body 6 is in this case arranged within a chamber formedby a tube 8, being in turn at a distance from an outer wall of the shaft2. This allows noise damping during the operation of the oscillationgenerator 5.

Furthermore, the resonant body 6 is configured as a hollow body, so thatthe piston rod 16 is guided axially through it. At its front end, theresonant body 6 is coupled to a tube-like oscillating body 10, viawhich—as is described in more detail hereinbelow—the oscillations arethen transmitted to the cartridge 30.

Once the handheld tool has been activated, the oscillation generator 5accordingly causes the oscillating body 10 to vibrate. At the same time,the pressure-generating means 15 push the piston rod 16 forward, i.e. tothe left in the illustrated case, in order to support the dispensing ofthe composite material 50. It is thus not necessary to actuate the tool1 separately in order to dispense the filling material 50.

In the following text, the cartridge 30 will be described in detail,this cartridge 30 being intended to be configured in particular as adisposable article. It consists preferably of two elements, a frontoutlet nozzle 35 and a tube-like component 31, which serves as anaccommodating container for the composite material 50. The accommodatingcontainer 31 is configured in a hollow-cylindrical manner and is coupledat its front end to the outlet aid 35, for example is welded oradhesively bonded thereto or is connected thereto by a press fit.Arranged in a movable manner at the rear end of the accommodatingcontainer 31 is a piston 40, which is pushed forward via the piston rod16 in order to dispense the filling material 50.

For ergonomic reasons, the outlet tube 35 is arranged in an angledmanner with respect to the container 31. It has an elongate cavity 37,which opens at its front end into the outlet opening 36. The elongatecavity 37 is in this case configured in particular in a conical manner,i.e. has a cross section that narrows increasingly in the direction ofthe outlet end 36. The result of this is that, while it is beingdispensed, the composite material 50 is continuously subject to shearstress and thus is heated through and liquefied more effectively.Compared to known solutions, in which the cannulas usually have acylindrical through-passage opening, improved liquefaction of thecomposite material 50 during the dispensing phase is accordinglyachieved. In this case—as is indicated in FIG. 3—the front end of thecannula 35 can also be designed in the form of a sphere 41. In thiscase, the cannula 35 can be used to compact the material alreadyintroduced into the tooth cavity by operating the spherical end region41 that is acted on by sound.

As can furthermore be gathered from the illustrations in FIGS. 2 and 3,the nozzle 35 has at its rear end facing the storage container 31 aflange-like end region 38, which is spaced apart slightly from the outercircumference of the storage container 31. Formed on the innercircumference of the flange-like end region 38 is a thread 39, via whichthe cartridge 30 can be screwed onto the oscillating body 10, which inturn has a thread 11, so that the configuration illustrated in FIG. 2 isachieved. In this case, it should be noted that, as an alternative tothe screw connection illustrated, the cartridge 30 could also beattached to the tool 1 via a bayonet connection or some other suitablequick-action connection. The arrangement of the connecting means in thecentral region of the cartridge 30 leads to a number of advantages,which will be explained in the following text.

Thus, first of all it is ensured that, on account of the direct couplingof the nozzle 35 to the oscillating body 10 or the arrangement of thethread 39 at the rear end of the cannula 35, more targeted action ofsound in order to liquefy the composite material 50 is achieved. It isin particular ensured that the sound can act on the composite material50 virtually over the entire section, with in particular the reductionin the cross section contributing thereto, since the material 50 comesfully into contact with the wall of the cannula 35. Since, furthermore,the storage container 31 is located as far as possible within theoscillating body 10, a smaller region of the surface of the cartridge 30is in contact with the outer side, and so a noise reduction duringoperation is achieved. Furthermore, it is not necessary for the wall ofthe container 31 to be formed in a manner stable under pressure, sinceit can now be supported directly on the oscillating body 10 and thusabsorbs all the pressure forces.

Finally, these advantages lead to it being possible for the cartridge 30to be configured in a simple manner as a disposable or single-useproduct. Hygiene regulations, in particular in dental practice, can becomplied with out great effort, it being ensured at the same time,however, that the composite material is liquefied effectively duringdispensing. This leads to a clear improvement in the operatingproperties of the handheld tool according to the invention.

In this case, it should be mentioned, in conclusion, that the cartridgeaccording to the invention could of course also be used in handheldtools which do not have means for automatically dispensing the fillingmaterial but rather have, for example, a lever mechanism to be actuatedseparately, as is known from DE 100 01 513 A1. In this case, too, theparticular arrangement of the cartridge on the tool contributes to animproved transmission of oscillations.

1. A handheld tool for dispensing a pasty filling material, theviscosity of which can be reduced by supplying oscillation energy, thetool having a tool housing, a detachable container for the pasty fillingmaterial, having an outlet nozzle at its front end, an oscillationgenerator having an oscillating body, and pressure-generating means forexerting pressure on the pasty filling material, wherein the oscillatingbody is detachably connected to the container in a central region of thecontainer.
 2. The handheld tool of claim 1, wherein the oscillating bodyis connected to the container via a quick-action connection.
 3. Thehandheld tool of claim 1, wherein the container has in a front region acannula which forms the outlet nozzle, wherein means for connecting thecontainer to the oscillating body are formed at the end of the cannula.4. The handheld tool of claim 3, wherein the cannula is a separateelement which is joined together to form the container with a componentthat forms an accommodating chamber for the filling material.
 5. Thehandheld tool of claim 4, wherein the component that forms theaccommodating chamber for the filling material is arranged, in the statearranged on the handheld tool, substantially within an accommodatingopening in the oscillating body.
 6. The handheld tool of claim 1,wherein the nozzle has a conical chamber which is directed toward thefront end and through which the filling material is channeled.
 7. Thehandheld tool of claim 1, wherein the container has in a rear region apressure piston, on which the pressure-generating means act to dispensethe filling material.
 8. The handheld tool of claim 7, wherein thepressure-generating means have a piston rod which acts on the pressurepiston in the container.
 9. The handheld tool of claim 8, wherein thecontainer has restoring means for pre-stressing the piston rod into astarting position.
 10. The handheld tool of claim 1, wherein theoscillation generator is a pneumatically drivable oscillation generator,wherein a common pressure supply for the oscillation generator and thepressure-generating means is provided.
 11. A handheld tool fordispensing a pasty filling material, the viscosity of which can bereduced by supplying oscillation energy, having a tool housing, adetachable container for the pasty filling material having an outletnozzle at a front end, an oscillation generator having an oscillatingbody, and pressure-generating means for exerting pressure on the pastyfilling material, wherein the container has in a rear region a pressurepiston and the pressure-generating means have a piston rod which acts onthe pressure piston in the container, wherein restoring means forpre-stressing the piston rod into a starting position are provided. 12.A container for use with a handheld tool for dispensing a pasty fillingmaterial, the viscosity of which can be reduced by supplying oscillationenergy, wherein the container is designed to accommodate the pastyfilling material and has at a front end an outlet nozzle for dispensingthe filling material, wherein the container has in a central regionmeans for detachably connecting it to the handheld tool.
 13. Thecontainer of claim 12, wherein the means for connecting the container tothe handheld tool are a quick-action connection.
 14. The container ofclaim 12, wherein the container has at a front end a cannula which formsthe outlet nozzle, wherein the means for connecting the container to thehandheld tool are formed at the end of the cannula.
 15. The container ofclaim 14, wherein the cannula is a separate element which is joinedtogether to form the container with a component that forms anaccommodating chamber for the filling material.
 16. The container ofclaim 12, wherein the nozzle has a conical chamber which is directedtoward the front end and through which the filling material ischanneled.
 17. The container of claim 12, wherein the container has in arear region a pressure piston.
 18. The handheld tool of claim 1, whereinthe oscillating body is connected to the container via a quick-actionscrew connection or a quick-action bayonet connection.
 19. The handheldtool of claim 8, wherein the restoring means comprise one or more springelements.
 20. The handheld tool of claim 11, wherein the restoring meanscomprise one or more spring elements.
 21. The container of claim 12,wherein the means for connecting the container to the handheld tool area quick-action screw connection or a quick-action bayonet connection.